diff options
Diffstat (limited to 'timebase.c')
| -rw-r--r-- | timebase.c | 45 |
1 files changed, 45 insertions, 0 deletions
@@ -326,6 +326,9 @@ void gpsd_century_update(struct gps_device_t *session, int century) } #endif /* NMEA0183_ENABLE */ +/* gpsd_gpstime_resolve() convert week/tow to UTC as a double + * deprecated, use gpsd_gpstime_resolv() + */ timestamp_t gpsd_gpstime_resolve(struct gps_device_t *session, unsigned short week, double tow) { @@ -365,4 +368,46 @@ timestamp_t gpsd_gpstime_resolve(struct gps_device_t *session, return t; } +/* gpsd_gpstime_resolv() convert week/tow to UTC as a timespec + */ +timespec_t gpsd_gpstime_resolv(struct gps_device_t *session, + unsigned short week, timespec_t tow) +{ + timespec_t t; + + /* + * This code detects and compensates for week counter rollovers that + * happen while gpsd is running. It will not save you if there was a + * rollover that confused the receiver before gpsd booted up. It *will* + * work even when Block IIF satellites increase the week counter width + * to 13 bits. + */ + if ((int)week < (session->context->gps_week & 0x3ff)) { + gpsd_log(&session->context->errout, LOG_INF, + "GPS week 10-bit rollover detected.\n"); + ++session->context->rollovers; + } + + /* + * This guard copes with both conventional GPS weeks and the "extended" + * 15-or-16-bit version with no wraparound that appears in Zodiac + * chips and is supposed to appear in the Geodetic Navigation + * Information (0x29) packet of SiRF chips. Some SiRF firmware versions + * (notably 231) actually ship the wrapped 10-bit week, despite what + * the protocol reference claims. + */ + if (week < 1024) + week += session->context->rollovers * 1024; + + t.tv_sec = GPS_EPOCH + (week * SECS_PER_WEEK) + tow.tv_sec; + t.tv_sec -= session->context->leap_seconds; + t.tv_nsec = tow.tv_nsec; + + session->context->gps_week = week; + session->context->gps_tow = tow.tv_sec + (tow.tv_nsec * 10e-9); + session->context->valid |= GPS_TIME_VALID; + + return t; +} + /* end */ |